Railway signaling system



Paiented July 29, 1941 2,251,117 nArLwAr SIGNALING SYSTEM Ralph K. Crooks, Sharpsburg, Pa.., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 30, 1939, Serial No. 311,891

Claims.

This invention relates to track circuit apparatus and more specifically to improved means to prevent false energization of a track relay in the event of failure of the insulated joints separating adjoining track sections.

It is an object of my invention to provide novel means operative on breaking down of the insulated joints separating adjoining sections to establish a circuit shunting the track circuit of one of the track sections to thereby provide a positive indication of the defective condition.

A further object of the invention is to provide improved track circuit apparatus which is arranged in such manner that on breaking down of the insulated joints separating adjoining track sections energy supplied to the rails of the section at one side of the defective joint cannot feed to the track relay for the section at the other side of the defective joint.

Another object of the invention is to provide improved track circuit apparatus of the type described and' which is applicable where either steady or coded direct or alternating current is employed in the track circuits, and in track stretches Where either steam or electric current is employed for propulsion purposes.

Other objects and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

I shall describe three forms of apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the drawing:

Fig. 1 is a diagrammatic view showing a stretch of railroad track equipped with one form of apparatus embodying my invention,

Fig. 2 is a view similar to Fig. 1 showing a modified form of apparatus embodying my invention, and

Fig. 3 is a view showing a stretch of track of a railroad employing electric current for propulsion purposes and equipped with apparatus embodying my invention.

Referring to Fig. 1 of the drawing there is shown therein a stretch of railway track having track rails i and 2 over which tranic normally moves in the direction indicated by the arrow, that is, from left to right. The railroad shown in 1 employs steam for propulsion purposes and. employs alternating current in the track circuits thereof.

The rails l and 2 have insulated joints 3 therein at suitable intervals to divide the track stretch into the usual track sections for signaling purposes. Two such sections are shown and are designated HT and IZT.

In addition to the usual insulated joints 3 separating adjoining track sections, one track rail of each section has another insulated joint 4 therein a short distance, such as one rail length, from the exit end of the section forming a short rail portion. In the diagram shown in Fig. 1 the insulated joint 4 is located in the track rail 2, while the short 'rail portion is designated 2a. The short rail portion of each section is connected by a wire 5 to the track rail l of the same section.

Each track section has located adjacent the exit end thereof a track transformer TT, the primary winding of which is supplied from a suitable source of alternating current, the terminals of which are designated BX and CK. One terminal of the secondary winding of the track transformer for each section is connected to track rail 2, and the other terminal of the secondary is connected through a current limiting reactor 6 to the short rail portion 2a. and thus through the connector 5 to the track rail l.

Each track section has adjacent the entrance end thereof an electroresponsive device in the form of a track relay TR of the alternating current type having one terminal of its winding connected to track rail I of the section, and the other terminal of its winding connected to the track rail 2 of the section.

The track relays control signals, not shown, which govern movement of trains through the track stretch. The control circuits for the signals are well known and in order to simplify the disclosure they have not been shown.

Under normal conditions with the track stretch vacant the track relays are energized by current supplied over the track rails of the associated section. The circuit for supplying energy to the winding of the track relay TB is traced from one terminal of the secondary winding of the track transformer IITT through track rail 2 of section HT, winding of relay llTRjtrack rail l of section HT, wire 5, short rail portion 2a of section HT, and reactor 6 to the other' terminal of the transformer secondary.

On entrance of a train into section HT the track relay l ITR. is shunted in the usual manner.

On failure of the insulated joint 4 separating the short rail portion 211. from the remainder of the rail of the section a circuit is established which short circuits the secondary of the track transformer for the section, and energy is not supplied to the track relay for the section. As a result the track relay contacts become released and condition the associated-signal, not shown, to display its most restrictive indication to thereby provide an indication of the defective condition.

In steam propulsion territory where the usual track circuit connections are employed, failure of the insulated joint in one track rail separating adjoining track sections does not permit energy to feed between the rails of the two sections, but breaking down of the insulated joints in both rails does have this effect, and the apparatus provided by this invention is arranged to prevent this feeding of energy between adjoining sections.

If, for example, the insulated joints 3'separating sections II T and IZT both become defective the connection 5 between the short rail portion 2a and the rail l of section IIT establishes a circuit shunting the winding of the track relay IZTR. so that energy supplied by the track transformer IITT cannot feed to the winding of the track relay IZTR. Instead the energy supplied by the tracktransiormer continues to feed to the winding of the track relay HTR over the circuittraced in detail above. At this time as the connection 5 shunts the winding of the track relay I2TR. energy supplied by the track transformer I2TT isv ineffective to energize the relay, and its contacts become released to condition the associated signal to display its stop indication to thereby provide an indication of the defective condition of the insulated joints.

The modification shown in Fig. 2 is similar to that shown in Fig. 1 in that steam is employed for propulsion purposes in the track stretch. The modification shown in Fig. 2 differs from that shown in Fig; 1' in that direct current is employed in the track. circuits thereof, while the short rail portion is located at the entrance end of each track section instead of at the exit end thereof as in the modification shownin Fig. 1.

Referring to Fig. 2' of the drawing the track stretch shown therein has track rails l5 and I6 over which traffic normally moves in the direction indicated by the arrow. The rails l5 and I6 have insulated joints IT therein to divide the track stretch into: track sections. Two such sections are shown and are designated IBT and [ST The rail 16 of each traclc section has therein a short distance, such as one rail length, from the entrance end of the section an insulated joint 20, leaving a short rail portion 16a which is insulated from the balance of the rail l6 of the same section and also from the rail I6 of'the adjoining section.

Each section has located' adjacent the exit end thereof a track battery B having one of its terminals connected to thetrack rail [5 and having its other terminal connected through a resistor 22 to the track rail l6.

Each track section has located adjacent the entrance end thereof a track relay TR having one terminal of its winding connected to the track rail l6 and having the other terminal of its winding connected to the short rail portion lSa, while the short rail portion is connected by a wire 23 to the rail I5 so that the track relay for each section normally receives energy over the track rails of the section from the track battery for the section. The circuit for energizing the winding of the track relay IBTR, is traced from one terminal of the battery 18B through the resi'stor 22, track rail l6, winding of relay IBTR, short rail portion Ida, wire 23 and rail 15 to the other terminal of the track battery.

If the insulated joint 2!] in a track section becomes defective a circuit is established shunting the winding of the track relay for the section with the result that the relay contacts become released and the signal, not shown, controlled thereby is conditioned to display its most restrictive indication.

If the insulated joints i1 separating two sections become defective a circuit shunting the track battery of the adjoining section in the rear is established. For example, if the joints l'l separating the sections IBT and I9T become defective a circuit shunting the track battery 18B is established. As a result energy is not supplied to the track relay ISTR and its contacts become released to condition the associated signal, not shown, to display its most restrictive indication.

While the modification shown in Fig. l of the drawing has the short rail portions located at the exit ends of the track sections and employs alternating current in the track circuits thereof, and while the system shown in Fig. 2 has the short; rail. portions located at the entrance ends of the track sections and employs direct current in the track circuits thereof, it should be understood that either type of current and either location of the short rail portions may be employed together if desired. Similarly, either steady or periodically interrupted energy may be employed in the track circuits.

The arrangement of track circuit connections provided by this invention is applicable to track stretches where electric current is employed for propulsion purposes as well as in territory where steam is employed for propulsion purposes, and Fig. 3 is a diagram illustrating the application of the invention to a track stretch where electric current is employed for propulsion purposes.

The track stretch shown in Fig. 3 has track rails 30 and 3| over which traffic normally moves in the direction indicated by the arrow, that is, from left to right.

The track rails 3!! and 3| have insulated joints 33 therein at suitable intervals to divide the track stretch into track sections for signaling purposes. Two such sections are shown and are designated 3 1T and 35T.

The track rails of each of the track sections have insulated joints 36 therein a short distance, such as one rail length, from the exit end of the section, leaving in the rail 30 a short rail portion disignated 30a and in the rail 3| a short rail portion designated 3| a.

The track sections are equipped with impedance bonds which serve to permit propulsion current to flow between the rails of adjoining sections. As shown each section has adjacent the entrance end thereof an impedance bond 38 of the usual construction having a winding having one end terminal connected to rail 30 and its other end terminal connected to rail 3f. The

, center or neutral terminal of the winding of each bond is connected by a neutral connector 39 of the short rail portions 39a and am at the exit end of the adjacent section in the rear.

Each of the track sections is provided with means in the form of a propulsion bond K to permit flow of current between the short rail portions and the balance of the rails of the section. Each of these propulsion bonds is similar to a transformer in construction, having a pair of windings and a magnetically permeable core.

while the winding 4| of each bond has one end terminal connected to the rail 30 and its other end terminal connected to the short rail portion 3011.

Each track section has a track transformer TT for supplying alternating current signal con-' trol energy to the rails of the section adjacent the exit end thereof. The secondary winding 43 of the transformer TT for each section has one terminal connected through a reactor 42 to track rail 3|, and has its other terminal connected to the short rail portion 3|a.

The primary windings of the track transformers are supplied with current from a source of alternating current the terminals of which are designated BX and CK.

Each track section has adjacent the entrance end thereof a track relay TR which controls a signal, not shown, which governs movement of trains in the track section. As shown the track relays are of the alternating current type, and each has a winding one terminal of which is connected to rail 30 and the other terminal of which is connected to rail 3|.

In operation signal control current supplied from the secondary winding of a track transformer, as for example the transformer 34TT, feeds through the windings of the propulsion bond 34K to the rails of the associated section.

Energy supplied from the secondary winding 43 of the transformer MTT flows through the winding 4!! of the propulsion bond 34K and this winding serves as the primary winding of an auto-transformer, while the windings 40 and 4| together form the secondary of the auto-transformer. The windings 40 and 4| are connected in series by the short rail portion 3|a, connector 39 and short rail portion 39a, while the ends of these windings are connected to the rails 30 and 3| of section 3 5T.

When an impulse of energy is supplied from the secondary winding of the track transformer SQ-TT to the propulsion bond winding 40, a flux is developed in the core of the bond with the result that energy is induced in the windings ll] and 4| serving as the secondary of an auto-transformer. The energy induced in the windings 4|] and 4| feeds therefrom through the track rails and 3| to the winding of the track relay 34TR. As a result of the auto-transformer action of the propulsion bond 34K the voltage of the current supplied to the track rails is substantially double that of the current supplied by the track transformer MTT, and this fact is taken into consideration in selecting the track transformer.

The impedance of the winding of the impedance bond 38 at the entrance end of the section MT is such that signal control current is substantially prevented from flowing through this winding between the rails 39 and 3| of the track section.

When a train enters a track section the track relay for that section is shunted in the usual manner, and the track relay contacts become released, and the signal controlled thereby is conditioned to display its most restrictive indication. 7

The arrangement shown in Fig. 3 permits propulsion current to flow freely between the rails of adjoining sections. For example, if a locomotive is present in section 3ST, and if it is assumed that the source of current is located at the left of section MT, the path for flow of current from the locomotive is traced through the rails 30 and 3| of section T, and through the two end portions of the winding of the impedance bond 38 to the neutral connector 39, from which ourrent flows to the short rail portions 360, and 3|a of section 34T.

The current then flows from the short rail portion 30a through the winding 4| of the propulsion bond 34K to rail 3|] of section SGT, while the current flows from the short rail portion am through winding 40 of propulsion bond 34K to the rail 3| of section MT.

The windings 40 and 4| of the propulsion bonds are arranged so that propulsion current flowing through them produces flux of opposite relative polarity in the core of the bond. Since the current in the two windings is substantially equal, the flux developed by the two windings neutralize each other and the impedance of the windings to the flow of propulsion current therethrough is relatively low.

The path for the flow of propulsion current from the rails of section 34T' to the rails of the adjoining section in the rear is similar to that traced for the flow of current from the rails of section 35T to the rails of section 34T. v

The system provided by this invention operates in the event an insulated joint separating two track sections becomes defective to prevent feeding of signal control current from the rails of one section to the rails of the other, while the track relay for the section at one side of the" defective joint will be shunted.

If, for example, either joint 33 separating sections MT and 35T becomes defective, a circuit is established shunting one half of the winding of the impedance bond 38 at the entrance end of the section 35T. The impedance of the other half of the winding of the impedance bond is so small that signal control current can readily flow between the rails 30 and 3|, and as a result too little current flows in the winding of the track relay 35TH to pick up the relay contacts.

The signal associated with the relay, therefore, is conditioned to display its most restrictive indication.

On breaking down of either joint 33 connec-' tion is established from one terminal of the secondary winding 43 of the track transformer S lTT to one terminal of the winding of the track relay 35TR, but no connection is established between the other terminal of the transformer Winding and the other terminal of the relay winding, and hence energy from the transformer does not feed over the defective joint to the track relay winding.

The system provided by this invention is also arranged so that failure of either insulated joint 36 separating the short rail portions from the remainder of the track section will be immediately detected.

If, for example, the joint 36 separating the short rail portion 3|a from the rail 3| of section 34T becomes defective a circuit is established short circuiting the secondary winding E3 of the track transformer and energy is not supplied therefrom to the track relay 34TR. The track relay contacts accordingly become released and condition the signal, not shown, to display its most restrictive indication to thereby provide an indication of the defective condition.

If the insulated joint 36 separating the short rail portion 36a from the remainder of the rail 30 of section 34T becomes defective a circuit is established which short circuits the winding M of propulsion bond 34K with the result that the auto-transformer action of this bond does not occur on the supply of energy by the track transformer 34TT, and too little current, or current of too low voltage is supplied to the track relay 34TH to pick up the relay contacts.

From the foregoing it will be seen that my invention provides improved track circuit apparatus which eliminates the possibility of false energization of a track relay in the event the insulated joints separating two track sections are defective. In each species provided by this invention each track section has at one end thereof a low resistance shunt connection between the traclt rails at that end of the section and that this connection prevents flow of signal control current between the rails of adjoining sections in the event the insulated joints separating the sections are defective.

Although I have herein shown and described only three forms of track circuit apparatus embodying my invention, it is understood that vari-- ous changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signaling system, in combination, a stretch of railway track having a first and a second track rail, each track rail having insulated joints therein to divide the track stretch into a plurality of successive track sections, the first rail of one of said sections having an insulated joint therein adjacent one end of said section to provide a short rail portion which is insulated from the remainder of the first rail of said section and from the first rail of the adjoining section, a connection between said short rail portion and the second rail of said section to thereby provide at said end of said one track section means operative on breaking down of the insulated joints between said one section and the adjoining section to establish a shunt connection between the rails of the adjoining section to thereby prevent objectionable feeding of energy between the rails of the adjoining section and the rails of said one section, said one track section having disposed adjacent one end thereof a current supply device and having disposed adjacent the other end thereof an electroresponsive device, the device at the end of the section at which the short rail portion is located having one of its terminals connected to the short rail portion and thereby to the second rail of said one section and having its other terminal connected to the first rail of said one section, the device at the other end of said one section having one of its terminals connected to the first rail and the other of its terminals connected to the second rail of said section, whereby the supply device associated with a track section normally supplies energy to the electroresponsive device of the said section over the track rails of the section.

2. In a railway signaling system, in combination, a stretch of railway track having a first and a second track rail, each track rail having insulated joints therein to divide the track stretch into a plurality of successive track sections, the first rail of one of said sections having an insulated joint therein adjacent one end of said sec tion to provide a short rail section which is insulated from the remainder of the first rail of the said section and from the first rail of the adjoining section, a connection between said short rail portion and the second rail of said one section to thereby provide at said end of said one track section means operative on breaking down of the insulated joints between said one section and the adjoining section to establish a shunt between the rails of the adjoining section to thereby prevent objectionable feeding of energy between the rails of the adjoining section and the rails of the said one section, a source of current having one terminal connected to the first rail of said one section and having its other terminal connected to the short rail portion and thereby to the second rail of the said one section, and an electroresponsive device connected between the first and second rails of said section adjacent the end thereof remote from said short rail portion and receiving energy from said source over the rails of said section.

3. In a railway signaling system, in combination, a stretch of railway track having a first and a second track rail, each track rail having insulated joints therein to divide the track stretch into a plurality of successive track sections, the first rail of one of said sections having an insulated joint therein adjacent one end of said section to provide a short rail section which is insulated from the remainder of the first rail of the said section and from the first rail of the adjoining section, a connection between said short rail portion and the second rail of said one section to thereby provide at said end of said one track section means operative on breaking down of the insulated joints between said one section and the adjoining section to esta lish a shunt between the rails of the adjoining section to thereby prevent objectionable feeding of energy between the rails of the adjoining section and'the rails of the said one section, an electroresponsive device having one of its terminals connected to the first rail of said one section and having its other terminal connected to said short rail portion and thereby to the second rail of said section, and a source of current connected between the first and second rails of said section adjacent the end thereof remote from said short rail portion and supplying energy to said electroresponsive device over the rails of said section.

4. In a railway signaling system, in combination, a stretch of railway track employing electric current for propulsion purposes, and having a pair of track rails each having insulated joints therein to divide the track stretch into a plurality of successive track sections, each rail of each track section having an auxiliary insulated joint therein adjacent one end of the section to provide short rail portions insulated from the rails of the adjoining section and from principal portions of the rails of the same section, each section having at one end thereof means for conducting propulsion current around the insulated joints separating the rails of said section from the short rail portions of the adjoining section, said means comprising an impedance bond having a winding having one of its end terminals connected to one of the principal rail portions and its other end terminal connected to the other of the principal rail portions of the section and having its center terminal connected to the short rail portions of the adjoining section, each section having means for conducting propulsion current around the auxiliary insulated joints therein, said means comprising a pair of windings each having one end terminal connected to the principal portion of a rail and its other end terminal connected to the short rail portion of the same rail, said windings being inductively associated with a magnetically permeable core in such manner that propulsion current flowing through said windings produces flux of opposite relative polarity in said core, whereby said fluxes substantially neutralize each other and the impedance of the windings to the flow of propulsion current is reduced to the minimum, each section having at one end thereof a current supply device and at the other end an electroresponsive signal control device, the device at the end of the section at which the short rail portions are located having one terminal connected to the short rail portion of one track rail and its other terminal connected to the principal portion of the same rail, the other device having one of its terminals connected to one rail and having its other terminal connected to the other rail of the said section.

5. In a railway signaling system, in combinaion, a stretch of railway track employing electric current for propulsion purposes and having a pair of track rails each having insulated joints therein to divide the track stretch into a plurality of successive track sections, each rail of each of said sections having adjacent the exit end of the section an auxiliary insulated joint to provide short rail portions insulated from the rails of the adjoining section in advance and from the principal portions of the rails of the same section, each section having at the entrance end thereof means to permit propulsion current to flow between the rails of said section and the short rail portions of the adjacent section in the rear, said means comprising an impedance bond having a winding having one of its end terminals connected to the principal portion of one rail and having its other end terminal connected to the principal portion of the other rail of the section and having its center terminal connected to the short rail portions of the adjoining section in the rear, each section having means for conducting propulsion current around the auxiliary insulated joints in the rails thereof, said means comprising a pair of windings each having one end terminal connected to the principal portion of a rail and its other end terminal connected to the short portion of the same rail, said windings being inductively associated with a magnetically permeable core in such manner that propulsion current flowing in said windings produces flux of opposite relative polarity in said core, whereby said fluxes substantially neutralize each other and the impedance of the windings to the flow of propulsion current is reduced to the minimum, each section having at the exit end thereof a source of alternating current signal .control energy, said source having one terminal connected to the principal portion of one rail and its other terminal connected to the short portion of the same rail, each section having an electroresponsive device at the entrance end thereof, said device having one of its terminals connected to the principal portion of one rail and the other of its terminals connected to the principal portion of the other rail of the said section.

RALPH K. CROOKS. 

